Benefits attributable to the inclusion of chlorhexidine in oral hygiene compositions have been widely documented in the literature. For example, Loe, Harald, ed., in Supplement No. 16, Vol. 21, 1986 to the Journal of Periodontal Research, presents seven published articles collectively entitled "Chlorhexidine in the Prevention and Treatment of Gingivitis." The Loe Supplement discusses various aspects of oral hygiene including: the effect of chlorhexidine gluconate mouth rinse on plaque bacteria; the efficacy of oral rinsing with chlorhexidine digluconate as compared with phenolic and plant alkaloid compounds; the results of a sixmonths' study of the effects of a chlorhexidine mouth rinse on gingivitis in adults; and other related topics. The Loe Supplement is representative of numerous published reports concerning the inclusion of chlorhexidine in oral hygiene compositions such as dentifrices and rinses.
Oral compositions containing chlorhexidine are also documented in the patented literature. For example, U.S. Pat. No. 3,842,168 to Colodney, entitled "Method of Preparing Stable Dentifrice," discloses a method of stabilizing a dentifrice containing alkali metal carboxyalkyl cellulose and 1,6-di-(p-chlorophenyl biguanidohexane) salt (i.e., chlorhexidine salt) against precipitation and flocculation. Also, U.S. Pat. No. 4,569,837, entitled "Pharmaceutical Preparation for Remedy of Periodontal Disease and Process for Production Thereof," discloses films which contain and release chlorhexidine gluconate and are suitable for insertion in the gingival sulcus.
Antibacterial compositions not intended for oral hygiene use may also contain chlorhexidine in various forms. For example, U.S. Pat. No. 4,666,896 to Warner, Jr. et al. discloses dermatological compositions containing water insoluble dinalidixate or diphosphanilate chlorhexidine salts. The insoluble salts are milled to a fine particle size and are dispersed within the compositions.
Unfortunately, when chlorhexidine (or one of its salts) is incorporated in an oral hygiene composition, the resultant product almost invariably has a strong, foul, bitter taste which flavoring agents can only partially mask. In addition, chlorhexidine (or one of its salts) stains tooth enamel an unsightly brown color, and the stains are resistant to removal by most if not all consumer dentifrices. These disadvantages present serious obstacles to the development of a product which provides optimal application of chlorhexidine to the mouth, teeth and gingiva, maintains cosmetic integrity of the tooth enamel, and avoids the foul taste of other chlorhexidine-containing compositions.